The GSX-R400 (initially called GSX-R in Japan, internal model code GK71B) was released in March 1984. It was the first mass-produced light-weight racer replica with an aluminum cradle frame and a liquid-cooled inline-four DOHC engine with four valves per cylinder. The, in those days, amazing machine was based on Yoshimura's TT-F3 racer GS1000R. The competitors, Yamaha FZ400R and Honda CBR400R were 13—31 kg (29—68 lbs) heavier than the new and quick GSX-R. 84 85